I'm trying the jetpack navigation and can't show the navigation back button when I move to a new fragment.
NavigationActivity.kt
class NavActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_navigation)
val toolbar = findViewById<Toolbar>(R.id.toolbar)
setSupportActionBar(toolbar)
val host: NavHostFragment = supportFragmentManager
.findFragmentById(R.id.navigation_graph) as NavHostFragment? ?: return
// Set up Navigation
val navController = host.navController
setupActionBarWithNavController(navController)
setupBottomNavMenu(navController)
}
private fun setupActionBarWithNavController(navController: NavController) {
setupActionBarWithNavController(this, navController)
}
private fun setupBottomNavMenu(navController: NavController) {
findViewById<BottomNavigationView>(R.id.bottom_nav_view)?.let { bottomNavView ->
NavigationUI.setupWithNavController(bottomNavView, navController)
}
}
}
activity_navigation.xml
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".views.NavActivity">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar"
android:layout_height="?attr/actionBarSize"
android:elevation="4dp"
android:background="?attr/colorPrimary"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
android:layout_width="match_parent">
</androidx.appcompat.widget.Toolbar>
<fragment
android:id="@+id/navigation_graph"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/toolbar"
app:navGraph="@navigation/navigation_graph"/>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/bottom_nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:menu="@menu/menu_bottom_nav" />
navigation_graph.xml
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
app:startDestination="@+id/launcher_home">
<fragment
android:id="@+id/launcher_home"
android:name="com.noisyninja.androidlistpoc.views.main.MainFragment"
android:label="@string/app_name"
tools:layout="@layout/fragment_main">
<action
android:id="@+id/next_action"
app:destination="@+id/detailFragment"
app:enterAnim="@anim/slide_in_right"
app:exitAnim="@anim/slide_out_left"
app:popEnterAnim="@anim/slide_in_left"
app:popExitAnim="@anim/slide_out_right" />
</fragment>
<fragment
android:id="@+id/detailFragment"
android:name="com.noisyninja.androidlistpoc.views.detail.DetailFragment"
android:label="DetailFragment" />
</navigation>
code for navigation:
/**
* opens detail activity
*/
override fun showDetail(view: View, me: Me) {
var bundle = Bundle()
bundle.putString("key", "value")
Navigation.findNavController(view).navigate(R.id.next_action, bundle, null)
}
As above when navigation to the second fragment the toolbar goes missing entirely and doesn't show the back button. Hitting the hardware back button also doesn't pop the detail view. The first hit has no effect, the second hit quits the app.
Edit : Your DetailFragment
contains the line
DataBindingUtil.setContentView<FragmentDetailBinding>(requireActivity(),
R.layout.fragment_detail)
which is resetting the content of your Activity to only be your fragment_detail
layout, wiping out the NavHostFragment and everything else.
You should be using DataBindingUtil.bind<FragmentDetailBinding>(view)!!
instead.
Original answer (you should still do this, but the above answer is actually what solves the problem)
Your ConstraintLayout
is missing quite a few constraints (your views should be a vertical chain , where every app:layout_constraintTop_toBottomOf
has an alternative app:layout_constraintBottom_toTopOf
on the other element, etc.).
Since you have a single set of three vertically aligned items, you don't need a ConstraintLayout
- just a LinearLayout
is enough:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".views.NavActivity">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar"
android:layout_height="?attr/actionBarSize"
android:elevation="4dp"
android:background="?attr/colorPrimary"
android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
android:layout_width="match_parent"/>
<fragment
android:id="@+id/navigation_graph"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="0dp"
app:defaultNavHost="true"
app:navGraph="@navigation/navigation_graph"/>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="@+id/bottom_nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:menu="@menu/menu_bottom_nav" />
</LinearLayout>
Override
this method in your Activity with nav_host_fragment
@Override
public boolean onSupportNavigateUp() {
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
return NavigationUI.navigateUp(navController, mAppBarConfiguration)
|| super.onSupportNavigateUp();
}
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